In cardiac, vascular, urology, laparoscopic cholecystectomy and other medical procedures using catheters, there has been an increasing need for large-diameter valves. These procedures use catheters having a wide range of diameters. These procedures may also use multiple catheters.
Current surgical valves fall into two basic categories, passive and active. A passive valve relies on the deformation of a resilient part by the catheter to form the required fluid-tight seal with the catheter. A recent example of a passive valve is described in U.S. Pat. No. 4,909,798, in which the valve has a longitudinally extended valve housing with a first opening and a central longitudinal passage communicating with an opposite second opening. A one-piece seal located in the longitudinally extended valve housing has a sealing neck having a relatively small opening that communicates with a sealing chamber. On the opposite side of the sealing chamber are sealing exit lips that are readily expansible to a diameter less than that of the valve housing when a catheter is inserted. This surgical valve does not accommodate a wide range of catheter diameters. A seal that exerts enough lateral pressure to seal around a small-diameter catheter applies too much friction when sealing a large-diameter catheter. Moreover, the lip-type seals tend not to seal uniformly around all of the circumference of the catheter.
An active surgical valve includes a mechanism that moves a seal into contact with the catheter when the catheter is in place in the valve. A common feature of such valves is a tube of a flexible material through which the catheter is inserted. A mechanism moves the flexible material into contact with the catheter.
Some valves, such as the valves shown in U.S. Pat. Nos. 3,977,400 and 4,243,034, use a simple vise-like arrangement with opposing jaws to bring the flexible material into contact with the catheter. With such an arrangement, the contact pressure between the flexible material and the catheter is very non-uniform around the circumference of the catheter. A development of this arrangement uses two pairs of opposing jaws perpendicular to one another to produce a more uniform contact pressure.
U.S. Pat. No. 3,970,089 describes a tube of a flexible material surrounded by an annular vessel into which a fluid can be pumped to apply pressure to the outer wall of the tube, and hence to move the inner wall of the tube into contact with the catheter. This arrangement provides a uniform contact pressure between the tube and the catheter, but the range of catheters that can be sealed without the wall of the tube buckling, and providing a leakage path, is limited.
U.S. Pat. No. 4,580,573 shows an arrangement in which a flexible tube has a rigid tube connected to each end. The catheter passes through the rigid tubes and the flexible tube. By rotating one of the rigid tubes axially relative to the other a twist is imposed on the flexible tube, which reduces the internal diameter of the flexible tube such that the inner wall of the flexible tube forms a seal with the catheter.
Current surgical valves have a tendency to leak, especially if multiple catheters are used. Additionally, current surgical valves can only be used with catheters having a relatively narrow range of diameters. Current large diameter surgical valves do not close completely and require that the catheter be left in place to maintain a seal. Current surgical valves require constant manipulation to maintain a seal around the catheter without excessive friction.